ESD Protection Circuit with RC-Triggered PMOS for High Voltage Latch-Up Prevention
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Solution Overview
Problem
Existing ESD protection circuits in semiconductor technology face challenges in high voltage applications, where SCR or NMOS-based circuits may cause latch-up failures due to insufficient holding voltage, and RC triggered PMOS transistors consume excessive die area.
Innovation Solution
The proposed ESD protection circuit incorporates a high voltage P type implanted region and a High Voltage N Well, forming a Zener diode and bipolar PNP transistor in series connection, which provides a higher breakdown voltage and efficient current path, and can also include a reverse diode and SCR in series for enhanced protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If SCR or NMOS based ESD protection circuits are used in high voltage applications, then the die area is reduced, but latch-up failure occurs due to insufficient holding voltage
Solution Approach 1:
The patent changes the voltage parameter characteristics by using a RC-triggered PMOS transistor configuration that provides a holding voltage greater than 5V, compared to the conventional SCR or NMOS circuits that have insufficient holding voltage. This parameter change resolves the latch-up failure issue while maintaining compact die area.
Solution Approach 2:
The patent employs a dynamic triggering mechanism using an RC circuit that activates the PMOS transistor only when needed (during ESD events). The circuit transitions from a high-impedance state to a low-impedance discharge path dynamically, providing high holding voltage only when required, thus avoiding latch-up failures.
2Reliability
If RC triggered PMOS transistor is used to achieve high holding voltage, then latch-up failure is prevented, but die area consumption increases
Solution Approach 1:
The RC-triggered PMOS transistor serves multiple functions: it acts as a voltage regulator to maintain holding voltage above 5V, provides ESD discharge path, and prevents latch-up failures. This multi-functionality allows achieving high reliability without proportionally increasing die area, as a single transistor performs multiple protective roles.
Solution Approach 2:
The patent applies the RC-triggered PMOS configuration specifically at critical I/O pads where ESD protection is most needed, rather than uniformly across the entire chip. This localized application optimizes the holding voltage provision while minimizing overall die area consumption.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration offers a reliable ESD protection with a higher breakdown voltage and optimized semiconductor die size, effectively preventing damage from voltage spikes and ensuring the internal circuits are protected.
Implementation Method 1
provides a higher breakdown voltage
Implementation Method 2
Electrostatic Discharge (ESD) is a rapid discharge that flows between two objects due to the built-up of static charge
Data Source
AI summary
A device comprises a high voltage N well and a high voltage P well over an N+ buried layer, a high voltage P-type implanted region in the high voltage N well, a first N+ region over the high voltage P-type implanted region and a P+ region and a second N+ region over the high voltage P well.